package com.cloudwave.trailends.utils.security;

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

/**
 * @description 
 * @author DolphinBoy
 * @email dolphinboyo@gmail.com
 * @date 2013-9-1 @time 下午8:48:27
 * 参考：http://stackoverflow.com/questions/4874311/badpaddingexception-in-android-encrypt
 */

public class StringEncrypter {
	Cipher ecipher;
	Cipher dcipher;

	public StringEncrypter(String password) {

	    // 8-bytes Salt
	    byte[] salt = {
	        (byte)0xA9, (byte)0x9B, (byte)0xC8, (byte)0x32,
	        (byte)0x56, (byte)0x34, (byte)0xE3, (byte)0x03
	    };

	    // Iteration count
	    int iterationCount = 19;

	    try {

	        KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, iterationCount);
	        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);

	        ecipher = Cipher.getInstance(key.getAlgorithm());
	        dcipher = Cipher.getInstance(key.getAlgorithm());

	        // Prepare the parameters to the cipthers
	        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);

	        ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
	        dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);

	    } catch (InvalidAlgorithmParameterException e) {
	        System.out.println("EXCEPTION: InvalidAlgorithmParameterException");
	    } catch (InvalidKeySpecException e) {
	        System.out.println("EXCEPTION: InvalidKeySpecException");
	    } catch (NoSuchPaddingException e) {
	        System.out.println("EXCEPTION: NoSuchPaddingException");
	    } catch (NoSuchAlgorithmException e) {
	        System.out.println("EXCEPTION: NoSuchAlgorithmException");
	    } catch (InvalidKeyException e) {
	        System.out.println("EXCEPTION: InvalidKeyException");
	    }
	}


	/**
	 * Takes a single String as an argument and returns an Encrypted version
	 * of that String.
	 * @param str String to be encrypted
	 * @return <code>String</code> Encrypted version of the provided String
	 */
	public byte[] encrypt(String str) {
	    try {
	        // Encode the string into bytes using utf-8
	        byte[] utf8 = str.getBytes("UTF8");

	        // Encrypt
	        byte[] enc = ecipher.doFinal(utf8);

	        // Encode bytes to base64 to get a string
	        //return new sun.misc.BASE64Encoder().encode(enc);
	        return enc;

	    } catch (BadPaddingException e) {
	    } catch (IllegalBlockSizeException e) {
	    } catch (UnsupportedEncodingException e) {
	    }
	    return null;
	}


	/**
	 * Takes a encrypted String as an argument, decrypts and returns the
	 * decrypted String.
	 * @param str Encrypted String to be decrypted
	 * @return <code>String</code> Decrypted version of the provided String
	 */
	public String decrypt(byte[] dec) {

	    try {

	        // Decode base64 to get bytes
	        //byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);
	        //byte[] dec = Base64Coder.decode(str);

	        // Decrypt
	        byte[] utf8 = dcipher.doFinal(dec);

	        // Decode using utf-8
	        return new String(utf8, "UTF8");

	    } catch (BadPaddingException e) {
	    } catch (IllegalBlockSizeException e) {
	    } catch (UnsupportedEncodingException e) {
	    }
	    return null;
	}
}
